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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include "mads/compression.h"
namespace MADS {
const char *const madsPackString = "MADSPACK";
const char *const FabInputExceededError = "FabDecompressor - Passed end of input buffer during decompression";
const char *const FabOutputExceededError = "FabDecompressor - Decompressed data exceeded specified size";
bool MadsPack::isCompressed(Common::SeekableReadStream *stream) {
// Check whether the passed stream is packed
char tempBuffer[8];
stream->seek(0);
if (stream->read(tempBuffer, 8) == 8) {
if (!strncmp(tempBuffer, madsPackString, 8))
return true;
}
return false;
}
MadsPack::MadsPack(Common::SeekableReadStream *stream) {
initialize(stream);
}
MadsPack::MadsPack(const Common::String &resourceName, MADSEngine *vm) {
File file(resourceName);
initialize(&file);
file.close();
}
void MadsPack::initialize(Common::SeekableReadStream *stream) {
if (!MadsPack::isCompressed(stream))
error("Attempted to decompress a resource that was not MadsPacked");
stream->seek(14);
_count = stream->readUint16LE();
_items = new MadsPackEntry[_count];
byte *headerData = new byte[0xA0];
byte *header = headerData;
stream->read(headerData, 0xA0);
for (int i = 0; i < _count; ++i, header += 10) {
// Get header data
_items[i]._type = (CompressionType)*header;
_items[i]._priority = *(header + 1);
_items[i]._size = READ_LE_UINT32(header + 2);
_items[i]._compressedSize = READ_LE_UINT32(header + 6);
byte *sourceData = new byte[_items[i]._compressedSize];
stream->read(sourceData, _items[i]._compressedSize);
switch (_items[i]._type) {
case COMPRESS_NONE:
// Entry isn't compressed
_items[i]._data = sourceData;
break;
case COMPRESS_FAB: {
// Decompress the entry
_items[i]._data = new byte[_items[i]._size];
FabDecompressor fab;
fab.decompress(sourceData, _items[i]._compressedSize, _items[i]._data, _items[i]._size);
delete[] sourceData;
break;
}
default:
error("Unknown compression type encountered");
}
}
delete[] headerData;
_dataOffset = stream->pos();
}
MadsPack::~MadsPack() {
for (int i = 0; i < _count; ++i)
delete[] _items[i]._data;
delete[] _items;
}
//--------------------------------------------------------------------------
void FabDecompressor::decompress(const byte *srcData, int srcSize, byte *destData, int destSize) {
byte copyLen, copyOfsShift, copyOfsMask, copyLenMask;
unsigned long copyOfs;
byte *destP;
// Validate that the data starts with the FAB header
if (strncmp((const char *)srcData, "FAB", 3) != 0)
error("FabDecompressor - Invalid compressed data");
int shiftVal = srcData[3];
if ((shiftVal < 10) || (shiftVal > 13))
error("FabDecompressor - Invalid shift start");
copyOfsShift = 16 - shiftVal;
copyOfsMask = 0xFF << (shiftVal - 8);
copyLenMask = (1 << copyOfsShift) - 1;
copyOfs = 0xFFFF0000;
destP = destData;
// Initialize data fields
_srcData = srcData;
_srcP = _srcData + 6;
_srcSize = srcSize;
_bitsLeft = 16;
_bitBuffer = READ_LE_UINT16(srcData + 4);
for (;;) {
if (getBit() == 0) {
if (getBit() == 0) {
copyLen = ((getBit() << 1) | getBit()) + 2;
copyOfs = *_srcP++ | 0xFFFFFF00;
} else {
copyOfs = (((_srcP[1] >> copyOfsShift) | copyOfsMask) << 8) | _srcP[0];
copyLen = _srcP[1] & copyLenMask;
_srcP += 2;
if (copyLen == 0) {
copyLen = *_srcP++;
if (copyLen == 0)
break;
else if (copyLen == 1)
continue;
else
copyLen++;
} else {
copyLen += 2;
}
copyOfs |= 0xFFFF0000;
}
while (copyLen-- > 0) {
if (destP - destData == destSize)
error(FabOutputExceededError);
*destP = destP[(signed int)copyOfs];
destP++;
}
} else {
if (_srcP - srcData == srcSize)
error(FabInputExceededError);
if (destP - destData == destSize)
error(FabOutputExceededError);
*destP++ = *_srcP++;
}
}
if (destP - destData != destSize)
error("FabDecompressor - Decompressed data does not match header decompressed size");
}
int FabDecompressor::getBit() {
_bitsLeft--;
if (_bitsLeft == 0) {
if (_srcP - _srcData == _srcSize)
error(FabInputExceededError);
_bitBuffer = (READ_LE_UINT16(_srcP) << 1) | (_bitBuffer & 1);
_srcP += 2;
_bitsLeft = 16;
}
int bit = _bitBuffer & 1;
_bitBuffer >>= 1;
return bit;
}
} // End of namespace MADS
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